Hard formation retractable drill bit



J. E. ORTLOFF HARDFORMATION RETRACTABLE DRILL BIT blov. 20, 1956 5 Sheets-Sheet 2 John E Oriloff Bn venbor Filed Jan. 29, 1952 Nov. 20, 1956 J. E. ORTLOFF 2,771,275

HARD FORMATION RETRACTABLE DRILL BIT Filed Jan. 29, 1952' Wit-j;

F1 (F9 QIQF Eorelqff @mmbop 7 (lbbornag Nov. 20, 1956 J. E. ORTLOFF HARD FORMATION RETRACTABLE DRILL BIT 5 Sheets-Sheet 4 Filed Jan. 29, 1952 Qfohrz OrilOff Gm/eager 5710. Cioborfrzeg J- E. ORTLOFF HARD FORMATION RETRACTABLE DRILL BIT 7 Nov. 20, 1956 5 Sheets-Sheet 5 Filed Jan. 29, 1952 Y a a \\\\W\\w\ Q Q Q Z 2 2 a llll l I Inventor John E. Orfloff Attorney United rates Patent Q HARD roRMArr-oN RETRACTABLE DRILL BIT John E. Ortlolf, Tulsa, Okla, assignor to Esso Research and Engineering Company, a corporation of Delaware Application January 29, 1952, Serial No. 268,394

6 Claims. (Cl. 255-61) This invention concerns a novel form of hard formation drill bit. The particular feature of the drill bit is the manner in which four cutting cones are arranged to permit insertion through and recovery from a drill stem without removing the drill stem from the bore hole in which the drill is employed. The drill is particularly characterized by the combination of a spring mechanism with suitable latching dogs of the apparatus serving to provide positive expansion and retraction of the cone cutters as desired.

In conventional rotary drilling, a suitable drill bit is fixed to coupled sections of pipe called a drill string. As the drill is operated, additional sections of pipe are added to the drill string. Upon failure of the drill bit or when, for any reason, it becomes necessary to replace or service the drill bit, it is necessary to remove the entire drill string from the bore hole in order to recover the drill bit. When the drill bit has been replaced as desired, it is then necessary to reconnect the string of tubing. The time required to conduct these operations in conventional drilling accounts for a substantial portion of the drilling costs. It is this factor which makes the provision of a suitable form of retractable drill bit particularly desirable. By provision of a suitable retractable bit it becomes practical to employ casing as the drill string, maintaining the casing in place during drilling, and using this casing for production after drilling is completed.

A suitable form of retractable drill bit of a nature to permit insertion and removal through the drill string itself must fulfill certain definite qualifications. First, it must remain in a folded or retracted position while it is being lowered through the drill pipe so that the drill will not jam or lock in the drill pipe inadvertently during lowering. Second, it must positively stop at the bottom of the drill string and expand to a cutting size greater than the diameter of the drill string, preferably while off the bottom of the hole. Third, the drill bit must enable transfer of weight and rotary torsional motion from the drill string to the drill bit in order to secure effective cutting action. Fourth, the drill bit must include means permitting positive retraction of the extended cutting elements to permit the drill bit to be pulled through the drill string without difliculty. Finally, it is necessary that a suitable retractable drill bit have fiuid passages arranged therein permitting passage and direction of drilling fluid to the bottom of the hole adjacent the drill cutters for lubrication of the drill bit and removal of drill cuttings.

The present invention suitably fulfills each of these qualifications by embodying certain improvements and novel features in a drill, providing a desirable and improved form of retractable drill bit.

The drill bit of this invention may be understood by reference to the accompanying drawings illustrating a preferred embodiment of the invention in which:

Figures 1 and 2, of which Figure 2 is the lower continuing extension of Figure 1, show the drill bit in locked extended cutting position;

Similarly, Figures 3 and 4, taken together, of which ise Figure 4 is the lower extension of Figure 3, show the drill bit in retracted position;

Figure 5 is a cross-section of Figure 5-5;

Figure 6 is a cross-section of Figure 4 along the line 66;

Figure 7 is a cross-section of the lower portion of the drill bit taken through the line 77 of Figure 2;

Figure 8 is a right side view of Figure 4, showing the lower portion of the drill bit when the cutting cones are held in retracted position;

Figure 9 is an elevational, cross-sectional view showing the upper portion of a modification of the drill bit described; and

Figure 10 shows the lower extension of the drill shown in Figure 9.

Figure 11 shows a side view of the apparatus illustrated in Figure 4 with the omission of the drill collar 1.

Figure 12 is a view in cross section of the apparatus which is illustrated in Figure 11.

In describing the invention reference will primarily be made to Figures 1 and 2 of the drawings. However, like reference numerals are applied to similar parts in the remaining figures of the drawings and reference may be made to other figures of the drawings for a better understanding of the apparatus described.

The drill bit is to be employed in conjunction with an especially designed drill collar 1. This drill collar may be fixed to a conventional drill string or a string of casing by means of a threaded coupling or the like. The internal diameter of the drill collar may be substantially that of the drill string with which the drill is used, while the external diameter may be somewhat greater than that of the drill string to provide increased structural strength. The drill collar is essentially a tubular member having an upper grooved portion 2, arranged as an annular groove in the collar, to provide :a shoulder 3 against which latching dogs may bear. A second annular groove 4 adjacent the lower termination of the drill collar similarly provides a shoulder 5 against which other latching dogs may bear.

The retractable drill itself consists of three principal essentially tubular elements, identified by numerals 6, 20, and 9. As will be seen, upper tubular element 20 and sleeve member 9 slidably receive support member 6, the latter extending substantially through the entire drill. A helical spring 7 is mounted on a median portion of tubular support member 6, bearing at its upper end against a collar 8 provided on member 6. The lower end of helical spring 7 bears against a sleeve 9 which encircles a lower portion of tubular member 6. Tubular member 6 extends downwardly through sleeve 9 to terminate as 1 along the line an enlarged head 10. Head 10 may be attached to tubular member 6 by threads or other suitable means to facilitate assembly. The head member 10 supports downwardly extending lugs 71 to which two cone cutter supporting arms 11 and 12 may be pivotally attached as by pins 70. Cutters, such as the cone type cutters 13 and 14 illustrated, may be suitably attached to the support- 'ng arms 11 and 12 by means of suitable bearings and trunnions. Sleeve 9 encircling tubular member 6 is pro-.

As described, consequently, sleeve 9 maintained in sliding relationship with tubular member 6, tends to be urged downwardly with respect to member 6 by spring 7. At the lower limit of downward movement, sleeve 9 is forced against member 10. The spring element thus serves to maintain the drill cutters of the apparatus in the retracted position illustrated in Figure 4, when tubular support member 6 is suitably suspended from above. The remaining elements associated with sleeve 9 which are essential for operation are the latching dogs 25 which are pivoted in slots of sleeve 9. Preferably three of these latching dogs are employed, as illustrated. These latching dogs are urged outwardly by leaf springs 26, and serve the function of latching in the lower groove 4 of the drill collar to permit elf-bottom extension of the drill bit as will be described.

Tubular member 6 extends upwardly in telescopic relationship with an enlarged tubular member 26. Tubular member 20 is provided with a conventional spearhead 21 at the upper termination thereof. A number of latching dogs 22, preferably three in number as illustrated, are pivotally fixed in slots provided in the tubu lar member 6 extending in part through matching slots in tubular member 20. These latching dogs are urged outwardly by leaf spring elements 23. When the slots provided in the outer tubular member 20 register with the slots and latching dogs of member 6, the latching dogs extend outwardly as shown in Figure 1. However, when member 20 is moved upwardly with respect to member 6, the latching dogs are forced into retracted position as shown in Figure 3. Extensions 24 provided on latching dogs 22, extend through the corresponding slots in sleeve member 20, bearing against the lower edge of the slots when the latches are in the retracted posi tion.

The arrangement of tubular member 6 and sleeve member 20 described is employed to control the extension of latching dogs 22. When the weight of the apparatus is borne by spearhead 21, the weight of the drill causes tubular member 6 to slide downwardly with respect to sleeve member 20 to which the spearhead is fixed. This maintains the members in the position shown in Figure 3 and maintains the latching dogs 22 in retracted position. The extensions 24 of these latching dogs, bearing on the edge of the slots in sleeve 20 serves to support the weight of the remaining elements of the drill. However, if sleeve 20 is permitted to slide downwardly with respect to tubular member 6, the slots provided in sleeve 20 will register with latching dogs 22 so that these latching dogs can be extended outwardly into latching position by the action of leaf springs 23.

With this description of the principal elements of the drill bit, the manner in which the drill bit operates may be understood. In this description of the operation of the drill bit, reference will also be made to remaining features of the apparatus which are illustrated but which have not heretofore been described in detail. Considering that it is desired to lower the drill bit through a drill string, the drill bit will be placed in the condition illustrated in Figures 3 and 4. This retracted position of the drill bit is automatically attained by supporting the apparatus by spearhead 21. For this purpose, a suitable wire line tool, having a releasable spearhead latching arrangement, will be attached to spearhead 21. The drill bit may then be lowered into the drill string. As the weight of the drill bit will be carried by the upper sleeve member 20, member 20 will maintain the latching dogs 22 in retracted position shown in Figure 3 as formerly described. The lower latching dogs 25 will be urged outwardly against the inside of the drill string as the apparatus is lowered, but will not impede lowering of the apparatus until these latching dogs contact the shoulder provided in the lower annular groove 4 cut in the drill collar. During the lowering operation, the cone cutters 11 and 12 will be positively held in retracted position by operation of spring 7 as described.

When the apparatus has been lowered to the point shown in Figure 4, latching dogs will encounter the shoulder 5 provided at the lower end of the drill collar. Further downward movement of sleeve 9 and the elements fixed to and supported by this sleeve will then be stopped. On continuing to lower the supporting cable of the apparatus, upper tubular member 20 will slide downwardly with respect to the inner tubular member 6. The Weight of tubular member 20 will be exerted on tubular member 6 through shoulder 8. The weight of tubular member 20 and of support member 6 and their attached parts will be sufiicient to compress spring 7, thus permitting tubular member 6 to slide downward with respect to member 9. Since wedge 17 is supported by sleeve 9 this sliding movement will bring the cone cutters 13 and 14 against the wedge 17 which will force the cutters and the aims 11 and 12 to which they are attached into the extended position illustrated in Figure 2. Thus, expansion of the bit off the bottom of the hole is achieved. The wire line tool that was used to lower the drill into place may then be released from spearhead 21 and removed from the drill string.

The drill string is then lowered until the four cone cutters contact the bottom of the hole. Drill collar 1 will then move downward with respect to the drill until the latching dogs 22 extend outwardly into the groove 2 of the drill collar as shown in Figure 1. It will be seen that the latching dogs are free to do this since when tubular member 20 has moved downwardly with respect to support member 6 during the expansion of the bit the slots in tubular member 20 have been placed into reg ister with the latching dogs. The bit will then be in the proper position for drilling, since weight on the bit can be applied through latching and driving dogs 22 from shoulder 3 in drill collar 1 to tubular member 6 and thence to the cone cutters.

It will be observed that a passageway for drilling mud is provided through the entire apparatus. This passage extends from ports cut in the upper termination of sleeve 20 adjacent the spearhead 21, through the interior of tubular member 6, to finally terminate in the opening 31 in head it It is a particular feature of the arrangement illustrated that a tubular extension 34 may be fixed to opening 31 so as to extend downwardly into a cup-shaped recess 35 formed in the wedge-shaped member 17 when the apparatus is in the position shown in Figure 2. A packing seal 36 may be fixed in this cup-shaped recess so that the tubular extension 34 may seal therein. Two or more channels 37 may be provided in the wedge-shaped member 17 to provide fluid openings just above and between the cone cutters.

In order to completely seal the fluid channel through the apparatus, it is desirable to position a rubber packing element 38 on tubular member 6 above collar 8. The tapered lower edge of sleeve 20 is adapted to slide between member 6 and packer 38 to force the packer into sealing position against the drill collar as shown in Figure 1. It will be noted that the provision of the upper sealing packer 38 and the lower packer 36 serves to provide a sealed fluid passage completely through the apparatus to a point adjacent the cutting cones without permitting by-passing of the drilling fluid.

The drill cutter supports dependent from member 10 are particularly shaped to provide a downwardly facing shoulder which is adapted to mate with an upwardly facing shoulder provided on the extensible cone cutter supports 11 and 12 when forced into the extended position. Consequently when the drill is forced to the position shown in Figure 2 these shoulders will contact each other, holding the extended cutters 13 and 14 in a locked drilling position.

In order to transmit drilling torque from the drill string, through the drill collar to the drill bit, one or more lugs 53 are positioned in groove 2 of the drill collar as shown in Figure 5. These lugs bear against the latching dogs 22, serving to transmit drilling torque through the drill bit to the cone cutters.

In removing the apparatus from the drill collar and through the drill stem when required, other particular features of the apparatus become apparent. To retrieve the drill, the drill string is first raised to lift the drill a few feet off the bottom of the bore hole. This permits the drill to slide downwardly within the drill collar until latching dogs 25 rest on shoulder 5 of annular groove 4 within the lower termination of the drill collar. When a retrieving tool is dropped over spearhead 21 and lifting force is applied, upper sleeve member 20 is pulled upwardly with respect to inner tubular member 6 so as to force the contraction of the upper latching dogs 22 to the position shown in Figure 3.

After latching dogs 22 are retracted to the position shown in Figure 3, continued lifting force applied to spearhead 21 will relieve the weight that has compressed spring 7, and tubular member 6 will slide through sleeve 9, thus permitting the head 10 with arms 11 and 12 attached to move away from wedge 17 and assume the position illustrated in Figure 4. The entire drill bit may then be withdrawn from the drill collar and up through drill string. Should the bit be balled up until member 6 will not slide through sleeve 9 and permit arms 11 and 12 to retract, continued upward force on spearhead 21 will pull the drill up until the back faces of latching dogs 25 contact the shoulder 59 in drill collar 1 as shown in Figure 2. Sleeve 9 will then be prevented from moving upward until tubular member 6 is pulled through sleeve 9 and slots 60 register with inner extensions 61 of latching dogs 25. At that time the bit will be fully retracted and the drill may be removed from the hole.

As emphasized, the type of retractable bit described is particularly intended to permit full extension of the cutters to cutting position off the bottom of the bore hole. In the event it is considered suitable to secure extension of the cutters by forcing the bit against the bottom of the bore hole, to some extent the drill construction can be simplified. A drill bit of this character is illustrated in Figures 9 and 10.

Referring first to Figure 9, it will be observed that the general arrangement of the drill is similar to that described. An inner tubular member 6 and an upper and outer sleeve member 20 .are employed in the same general manner as has been described. However, the groove 2 positioned in an upper portion of the drill collar 1 is particularly shaped as illustrated to provide a ledge portion of the groove designated by numeral 71. The latching dog 22 is thus adapted to catch on ledge 71 of groove 2 so as to hold the entire drill apparatus from dropping downwardly through the drill collar. As a result it is possible to dispense with the lower annular groove 4 of the drill collar of the nature shown in Figure Zand Figure 3. Similarly the latching dogs 25 of these figures are no longer necessitated. As a result the lower portion of the drill to be employed with the construction of Figure 9 is of the nature shown in Figure 10.

The operation of the drill illustrated in Figure 9 and 10 is similar to that formerly described. However, to secure extension of the cutters, it is necessary to lower the drill string so that contact against the bottom of the bore hole will provide the necessary force to move sleeve 9 upwardly with respect to tubular member 6 to force extension of the cutters 13 and 14. It will be observed that latching dogs 22 prevent upward movement of the apparatus in the drill collar to permit extension in this manner when the drill string is lowered.

Employing the apparatus of Figures 9 and 10, it is preferred to drop the drill downwardly through the drill string. For this purpose a shear pin 62 is preferably provided, passing through sleeve member 20 and fastening in tubular support member 6. This shear pin serves to hold the slots of sleeve member 20 in register with latches 22. Consequently, as the drill bit is dropped through the drill string, latches 22 will remain in the extended position so that when the drill bit reaches annular groove 2, latches 22 will catch therein to prevent the drill from dropping completely through the drill collar.

A particularly desirable feature of the apparatus of Figures 9 and 10 concerns provision for slowing the drill as it drops through the drill string. For this purpose an enlarged central chamber 63 is preferably positioned in the upper termination of support member 6. A check valve arrangement 64 is positioned at the upper end of chamber 63 in the manner illustrated. Thus a web member 65 is fixed in the upper opening of member 6. Web member 65 includes a restricted collar element adapted to support the valve stem of valve 64. Valve 64 is shaped to fit against the upper inner surface of chamber 63 so as to seal the passageway therethrough leaving the restricted channel 66 through the valve stem itself. However, when valve 64 drops to the downward position illustrated in Figure 9, a substantially greater fluid passage is available through the annular space around collar 65 of the web member.

Employed in conjunction with this check valve arrangement is a flexible packer element 67 which may be positioned in the external wall of support member 6 just above the spring 7. Packer member 67 is employed to seal one or more ports cut through member 6. When a positive pressure is provided within the tubular passage of tubular member 6, the packer is thus extended so as to contact and press against the drill collar 1.

Consequently, when a drill bit of this construction is dropped into a drill string, fluid will be forced upwardly through the lower tubular member 34 and through the central passage provided in tubular member 6. Passage of the fluid upwardly through the drill in this manner forces valve 64 to fit against the upper termination of member 6. As a result the fluid is forced to pass through the restricted opening 66 in the valve stem. This serves to build up a positive pressure within support member 6 which in turn serves to expand the packer Element 67 against the drill collar. As a result dropping of the drill through the drill string is slowed to a desirable extent.

It may be observed that this action is self-regulated. If packer 67, for example, were extended so fully as to stop dropping of the drill, the positive pressure within member 6 would be eliminated. This would cause packer 67 to contract, permitting the drill to continue to drop.

In order to remove the drill bit of Figures 9 and 10 from the drill string after completion of drilling operations, a retrieving tool is dropped through the drill string to engage the spearhead 21. When this occurs, shear pin 62 will be broken permitting sleeve 20 to slide upwardly so as to retract the latching dogs 22. in other respects the retraction operation will be of the nature previously described.

What is claimed is:

l. A retractable drill bit assembly comprising in combination a vertically disposed drill collar; an elongated vertically disposed tubular element; a sleeve element surrounding and in vertical movable relation with a lower portion of said tubular element; resilient means coacting with said tubular element and said sleeve element to yieldably restrain downward movement of said tubular element relative to said sleeve element; a tubular member surrounding and in vertical movable relation with an upper portion of said tubular element; interengaging means between said tubular member and said tubular element to limit movement of said tubular member upward relative to said tubular element; means interconnecting said tubular member and said tubular element to thrust said tubular element vertically downward relative to said sleeve element; means attachable to said tubular member adapted to lower said tubular member, said tubular element and said sleeve element within said drill collar; releasable latching means disposed in a cooperative arrangement between the drill collar and the sleeve element to limit downward movement of said sleeve element relative to said drill collar; a pair of oppositely disposed downwardly depending supports fixed to said sleeve element; a first pair of cutter elements; one of said cutter elements being mounted on the lower end of each said depending support; a second pair of oppositely disposed cutter elements depending from and pivotally mounted on the lower end of said tubular element; a Wedge element supported by and between said depending supports and arranged to expand said second pair of cutter elements with respect to said tubular element upon downward movement of the tubular element, said second pair of cutter elements in expanded condition being substantially at right angles to and laterally between said first pair of cutter elements; means for moving said drill collar vertically downward relative to said sleeve element; second releasable latching means disposed in a cooperative arrangement between said drill collar and said tubular element to limit downward movement of the drill collar relative to the tubular element; and means to rotate said drill collar in unison with said tubular element and said sleeve element.

2. An apparatus as defined in claim 1 in which conduit means are provided Within .the apparatus to direct drilling fluid to the cutter elements.

3. An apparatus as defined in claim 1 in which the tubular element includes a packing element arranged to form a fluid seal in the annular space between the tubular element and the drill collar.

4. An apparatus as defined in claim 1 including a pivot within said tubular element vertically intermediate said tubular member and said sleeve element, and an elastic packing element sealed over said pivot and arranged such that positive pressure within the tubular ele ment expands said packing element against the drill collar to provide a fluid-tight seal in the annular space between the tubular element and the drill collar.

5. An apparatus as defined in claim 1 including check valve means positioned in the upper termination of the tubular element, said check valve means being of a character to pass relatively greater flow of fluid in a downward direction than in an upward direction.

6. A retractable drill bit assembly comprising in combination a vertically disposed tubular element, an enlarged shoulder at the lower end of said tubular element and a second enlarged shoulder vertically intermediate the ends of said tubular element, a sleeve element surrounding and in vertical movable relation with said tubular element, said sleeve element positioned intermediate and spaced from both said shoulders, resil-ient:means vertically inter mediate said upper shoulder and said;sleeveelernent; arranged to urge the sleeve element toward said lower shoulder, a tubular drill collar arrangecllt'o receive said tubular element and said sleeve elemenn'retract-able latch: ing means disposed in a cooperative arrangement between said drill collar'and said sleeve element to limit movement of the sleeve element downward through the drill collar, a tubular member surrounding said tubular element and positioned above said upper shoulder, supporting means adapted to suspend said tubular member, means limiting movement of said tubular member vertically upward relative to said tubular element, said tubular member being arranged upon downward movementrelalive to said tubular element to compress said resilient means and to thrust said tubular element vertically downward relative to said sleeve element, a pair of oppositely disposed downwardly dependent supports fixed to said sleeve element, a first pair of cutter element-s, one of said cutter elements being mounted on the lower end of each said dependent support, a second pair of oppositely disposed cutter elements dependent from and pivotally mounted to said lower shoulder of said tubular element, a wedge element supported by and between said dependent supports and arranged to expand said second pair of cutter elements laterally outward upon downward movement of said tubular element, said second pair of cutter elements being substantially at right angles to and positioned between said first pair of cutter elements in the expanded condition, means for moving said drill collar vertically downward relative to said sleeve element, retractable latching means disposed in a cooperative arrangement between said drill collar and said tubular element to limit vertically downward movement of the drill collar relative to the tubular element, and means to rotate said drill collar, said sleeve element and said tubular member in unison.

References Cited in the file of this patent UNITED STATES PATENTS 465,103 Wegner Dec. 15, 1891 1,202,727 Keck Oct. 24, 1916 1,821,473 Mercer Sept. 1, 1931 1,909,817 Dodds May 16, 1933' 2,239,996 Chappell Apr. 29, 1941 2,330,083 Sewell Sept. 21, 1943 2,338,670 Sewell Ian. 4, 1944 

